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"1 Mdel) H` H ELBREG DENTAL AND SURGICAL CHAIR.

No. 589,499. Patented Sept.'7,1897` FIE- F I fui/5mm".-

NiTnD STATES PATENT Prien.

HENRY H. ELBREG, `OF INDIANAPOLIS, INDIANA.

DENTAL AND SURGICAL CHAIR.l

SPECIFICATION' forming part of Letters Patent No. 589,499, dated September 7, 1897. Y

Application filed July 28, 1894. Serial No. 518,830. (No model.)

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Be it known that I, HENRY ll. ELBREG, a citizen of the United States, and a resident of Indianapolis, in the county of Marion and State of Indiana, have invented certain new and useful Improvements in Dentaland Surgical Chairs, of which the following is a speciiication.

My invention relates to dental and surgical chairs, and particularly to means for adjusting the frame to any desired position.

The invention will be first fully described in connection with the accompanying drawings, and then particularly referred to and pointed out in the claim.

Referring to the drawings, in which like parts are indicated by similar reference-letters wherever they occur throughout the various views, Figure l is a central vertical sectional view of a dental and surgical chair provided with my improvements, part of the chair-supporting column being shown in elevation. Fig. 2 is a transverse sectional. view taken through line oc of Fig. l. Fig. 3 is an inverted plan view of part of the seat, illustrating the means for adjusting the chairframe around its axis and at an inclination thereto. Figs. 5L and 5 are enlarged detailed views of some of the parts.

The chair-frame A is of ordinary construction, except the bottom board or support a, for an upholstered seat. The body of the base is made, preferably, of a single casting and comprises two cylinders and an intermediate air-duct communicating from one cylinder to the other. The larger cylinderB is bored out true to receive the column C, the lower end of which within the cylinder is a piston preferably formed by a cup-leather packing cto iit air-tight within the cylinder. A smaller cylinder D is the barrel of an airpump fitted with a piston d, the rod d of which extends below the barrel and is coupled by a hinged joint to the piston at its upper end, its lower end being pivoted on the pin in the ends of the bifurcated treadle or lever E. The arms c of the lever are curved around upon opposite sides of the cylinder B and are fulcrumed upon pins e', which pass through the lever-arms and are secured in the cylinder B. The lower end of the cylinder B is fitted with an air-tight cap or plug` b. The legs B', which support the cylinder B, of which there are preferably four, may be either cast integral with said cylinder or secured to the outside thereof by bolts.

' The upper end of the air-pump connects with the cylinderB near its lower end through the air-duct cl2, the passage from the airpump to the duct being provided with a cheekvalve d3, which is shown in the drawings as an ordinary ball-valve, but any well-known form of. check-valve may be employed. The passage from the air-duct to the cylinder Bis controlled by a three-way cock F, by means of which air is admitted from the pump to the cylinder B or discharged therefrom tothe openY air. The foot-piece e2 is preferably hinged to the end of thelever E aud-provided with a toe-strap, by which. the lever may be drawn up and piston d ofthe air-pump retracted. The same result will be accomplished, of course, by a spring placed Linder the long arm of the lever E to exert an upward'pressure upon it when the pressure of the 'foot is taken away.

The air-chamber is a well-known construction. The air is supplied to the pump-chamber through its lower open end. The piston of the air-chamber is a cup-rubber secured upon the plunger, which does not closely fit the pump-chamber. The upward pressure of the air will collapse the cup-rubber and supply the upper portion of the chamber with air, and when the treadle is pressed down the air in the upper portion will expand the rubbercup against the walls of the pumpcylinder and force the air through the upper channel down through the supply-cock and into the chamber I3. 1

The upper end of the column C` terminates in two curved arms c and a central vertical extension c2 to support the chair-frame. To the under side of the chair-frame is secured a circular ring or plate G, the opposite sides of the ring being united by a diametrical transverse bar g, which has projecting down centrally from it a perforated lug to pass'into the upper end of the slot in the extension c2. A journal-pin passing through the ends of the extension c and through the lug projecting down from the transverse bar serves as a pivot to imite the plate to the upper end of said extension. A semicircular segment g',

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uniting the opposite sides of the ring,` G, plays in the lower part of the slot in the extension c2, and a set-screw c3, tapped through one wall of the extension and bearing upon the side of the segment g', locks the chair in whatever position it may be tilted. rl`l1e ring G is secured to the under side of the seat-support a by clips g2, lof which there may be any desired number, the clips being secured irmly to the platform a and projecting over the face of the ring` to permit the chair-frame to be turned around the column, the clips serving` as seats or tracks forthe ring G. In place of the clips g2 a recessed outer ring could of course be employed.

The upper ends of the curved arms c have semicircular bearings to receive the journalpins g3, which are formed upon the ends of studs which project down from the ring G. The ring G, transverse bar g, thc segment g, and studs g3 are all cast in a single piece. It will be seen that by this means the chairframe can be turned around its axis in any desired position and tilted back, forward, or held vertically, as shown in the drawings, by simply loosening the set-screw c3 and tightening it up again when the chair assumes the position desired.

To save metal, the column or follower C is cast hollow to near its upper end and is fitted to slide through an upper cap D', which, with the cup-leather packing,` and the rin gs which keep it in place, serve as `Guides to insure a steady perpendicular movement of the fot lower.

' In a dental and surgical chair, the combination of the base, the follower, having an upward slotted extension, the chainseat, the rin g, Gr, secu red to the chair-seat and havin ga downwardlyprojecting perforated lug to enter the slotted, extension of the follower, downwardly-projecting studs having horizontal journal-pins extendimg` from them, a downwardlyextending segment, g', adapted to traverse the slot in said upward extension of the follower, curved arms extending upon opposite sides of said central extension and having bearings in their upper ends to receive the journal-studs, g, and a set-screw tapped through .one of the slotted walls of said upper extension to bear upon the segment and hold it firm when adjusted, substantially as shown and described.

HENRY ll. ELBREG. Witn esses:

W. H. GnrMEs, 'FRANK DAcLisII. 

